The invention relates to a method and apparatus for continuously intensively wetting a flat article, especially a textile strip and the like.
In the working of wool goods and the like, the moistening or wetting of the filaments or fiber plays a decisive roll. English cloth, for example, owes its world wide reputation substantially to the fact that the water bound to the wool fibers is somewhat greater in quantity than in the best cloth of German and/or Italian origin. The reason for this is that the English climate has an excessive amount of moisture. However, by further economizing and increasing production output the time for manufacture is still less, because the usual pauses for climatizing the wool can be omitted. The long known "synthetic relaxation periods", e.g. by wetting steps, are only partially successful. The wetting methods known up to now fulfill the desired requirements only incompletely, because the atomization of the water is not fine enough, i.e. leads to droplets which are too large, so that only the material upper surfaces are wet, but not the interior of the wool material, particularly fibers in its central portion or core.
The wetting devices on the market currently operate according to different methods, e.g.:
1. Spraying of water by nozzles or rotors:
The moisture increase obtainable in that in the material is limited to about 8 to 12%. With larger amounts (often over 5%), an uneven effect often results. At those locations, where the water jet has impinged, strips are formed on the goods. Additional problems arise because of calcium salt deposition in the nozzles or rotors.
2. Aeration Units:
These units, e.g. mist generators or the like, provide a comparatively good uniformity over the entire goods width, when suitable machines with uniform suction capabilities are used, which draw the provided moisture through the goods. The obtainable effective moisturizing value are however comparatively low.
3. Devices for Wetting the Goods by Application of a Liquid Film.
These devices also have only limited applicability for wool or wool mixed textiles, because again inhomogeneities arise in pads, because of breakdown of the liquid film (formation of flecks, drops, schlieren and the like).
The correct and above all uniform wetting of wool goods and the like is however entirely important, indeed even decisive for the fixing process, especially to obtain a permanent fixing in wet (Flat-Setting Hydrosurface fixing) and in the dry state (permanent decatizing). In the hydrosurface fixing performed presently, one works the fixing material in the wet state, i.e. after the squeeze out process of the pad or the like at a residual moisture content of about 50 to 70%, according to the qualities of the pad or the like.
These known methods have a high cost, because much energy is necessary for drying, to bring the wet goods after fixing again to a normal moisture content. Scientific tests one year ago have however already shown that one obtains the best fixing values, e.g. with wool goods, between 25 to 35% moisture. Such values have not been obtained up to now in practice.
With total wetting or immersion in water in a water bath and subsequent squeezing out methods a limiting content of about 50% moisture can be obtained. On the other hand the moisture of the dried goods amounts to a maximum of from 10 to 12%, whereby these values must only be momentary results. The moisture has not gone deeply into the material and is easily returned to the environment by evaporation--unfortunately in a nonuniform manner. The result is a nonuniform wetting effect leading to an equivalently nonuniform fixing effect.
A strip free and intensively operating wetting apparatus, which operates continuously with a speed of at least 16 to 25 m/min goods transport speed and meets the desired requirements has not been available up to now.